Final answer:
Lizzie's grade percentage is the highest.
Step-by-step explanation:
To compare Gracie and Lizzie's grades, we need to convert Gracie's grade from a fraction to a percentage. Gracie earned 150 out of 200, which is equivalent to (150/200) * 100 = 75%.
Now that we have both grades as percentages, we can compare them. Lizzie earned 92% and Gracie earned 75%. Therefore, Lizzie's grade percentage is the highest.